This invention relates to a rust preventive agent comprising a novel hydroxypolybasic acid salt compound.
Various rust preventive agents have been proposed heretofore, but, preventives which exhibit low toxicity and are usable in a wide range of uses, are few, and no preventive which shows preventive effect for various kind of metals simultaneously is hitherto known. Examples of rust preventive agents of this kind include, petroleum sulfonic acid salt, sorbitan monooleic acid ester, metal soaps, etc. as oil-soluble rust preventive agents inorganic salts such as chromate, phosphate, and nitrite as water soluble rust preventive agent, and ethanolamine, benzotriazole, alkylphosphate-containing surface active agents, long chain quaternary ammonium halides, and higher amines, as water-oil soluble rust preventive agents. However, these rust preventive agents exhibit various disadvantages. That is, the solubility of some preventives is low in specific solvents, some are effective only on specific metals, and some preventives such as chromates cause the pollution which makes the preventives unusable in some cases. Furthermore, mixtures of a plurality of rust preventives have been proposed to eliminate above mentioned disadvantages, but the mixing not always results in the production of a rust preventive agent which exhibits an integrated advantage of each preventive. In some cases both preventives are immiscible with each other but mixtures exhibit disadvantages of each preventive, the life of effect is shortened, and some mixtures may yield carcinogens. For example, a mixture of nitrites and lower amines yields nitrozoamines.
Some of the inventors of this application had investigated the method for production of hydroxycarboxylic acids and esters thereof. This was followed up with the hard investigation of the application of the hydroxycarboxylic acids and esters thereof, and found that some kinds of salt having a cyclohexane ring exhibit practical advantages such as low toxicity, safety, and low-foaming, and additionally excellent rust preventive properties for various metals. Thus, this invention has been determined on the basis of this observation.